With the civil war raging in Syria and a porous border between Syria and Iraq's Anbar and Nineveh Provinces that has allowed militants – many of them jihadis in the style of Al Qaeda – to flow back and forth pretty much at will, Iraq's central government has a major challenge on its hands. It doesn't help that Iraq has parliamentary elections scheduled for this April and that its political polarization breaks down largely on sectarian lines.

But the country is not "on the brink" or "about to implode," if these stock phrases are meant to imply Iraq's impending descent into the depths of savagery that swept the country in 2005-07 or that Syria, with more than 150,000 dead, is experiencing now with its war.

Al Qaeda has taken over Anbar Province.

The first challenge is defining "Al Qaeda." Since the moment that a group calling itself Al Qaeda in Iraq was established in the country, shortly after the US-led invasion that overthrew Saddam Hussein in 2003, there's been a lot of confusion about the precise nature of the connection between the Sunni jihadis fighting inside the country and the original Al Qaeda led by Osama bin Laden.

Bin Laden and his successor Ayman al-Zawahiri saw the US invasion as a great opportunity and got in contact with the group, which was then run by the Jordanian Abu Musab al-Zarqawi (killed in a US airstrike in 2006). By 2004, Mr. Zarqawi had given an bay'a, an oath of allegiance, to bin Laden, and in the media narrative the two groups became intertwined.

But Zarqawi rarely followed orders from Al Qaeda central in Pakistan and Afghanistan – and a string of communications between his group and Zarqawi recovered by US forces during the war showed an enormous amount of frustration from Al Qaeda central over how its supposed Iraqi affiliate wouldn't do as it was told.

Part of the problem was that the militants fighting in Iraq had to cooperate with local Sunnis angry at the US occupation of the country – and the Shiite rise it was enabling – and less interested in Al Qaeda's mission of global jihad to create a multinational caliphate.

The fact that the Iraqi group's goals were largely national was clear as early as October 2006, when the group changed its name to the Islamic State in Iraq. It has also been made clear by the lack of any plots targeting the US or its European allies – something that would be a top objective if bin Laden and Zawahiri had control over the organization.

Ok, but Al Qaeda's fellow travelers have seized control of Fallujah and Ramadi, right?

Well, again, not exactly.

The Sunni Arab tribes along the Euphrates River in Syria and Iraq's Anbar Province have strong cultural and familial ties, and many Syrians flocked to Iraq to fight the US and its allies in the area in the mid-2000s. That's a key reason that the Islamic State in Iraq was able to merge relatively seamlessly with Syrian jihadis to become the Islamic State in Iraq and the Levant (ISIS) last year.

But while the group has been on a high the past few weeks, roaming relatively unhindered and prompting the Iraqi police to abandon their posts in both towns, "controlling" is something else.

During the US war in Iraq, the group quickly wore out its welcome with the major local tribal confederations and the general public. Summary executions of locals for violating Islamic law, floggings, and general contempt for tribal practices and authority saw to that – as did the direct threat they posed to the economic interests of powerful figures in the region, who had long controlled lucrative smuggling routes and didn't appreciate the interference of the so-called mujahideen. That opened the door for the Sahwa, or "awakening," in which Sunni Arab tribes took up arms against the jihadis in exchange for money and political influence promised by the US military.

The same dynamics are in place today. Anbar hates and fears the central government in Baghdad since, after all, the Shiite-dominated government of Prime Minister Nouri al-Maliki has treated the region and its leaders like dirt. But many leading tribal figures don't much like the jihadis either. They may passively support them, or even join forces with them against what they see as a greater enemy – the fighting in Fallujah and Ramadi was touched off by Mr. Maliki's decision to use the military to violently clear year-old protest encampments against his government on Dec. 30. But longterm, they don't want to be run by any outsiders.

What this means is that while Fallujah and Ramadi are clearly not in the government's control, they're also not really in "Al Qaeda's" control either. And many of the tribal figures who have fought government forces in recent days have framed their struggle in nationalist terms, referring to Maliki's government as doing the bidding of Iran against the interests of the Iraqi nation. But others have tentatively sided with the government to fight ISIS, and some are remaining on the sidelines.

Shiite-Sunni hatred is driving all this, right?

Well, no. At least not exactly.

The Sunni-Shiite divide in Iraq does drive much of national politics. But it's far from the whole story. Intermarriage between the sects is common, most Sunnis and Shiites still list "Iraqi" as their core identity, many of the largest tribal confederations contain both – and, at any rate, the divide is drawn by power and money, not dispute over the nature of Muslim worship. Saddam Hussein's Baath Party, the backbone of his murderous secular dictatorship, was open to Shiites as well as Sunnis, and many Shiites joined up for the economic and social advantages it conferred.

This is not to say that sectarian hatred isn't real, or wasn't a crucial component of the darkest days of the civil war. Sectarian death squads roamed the country in 2006 and 2007, torturing and killing people purely for their religious beliefs. In traditionally mixed cities like Baghdad, whole neighborhoods were depopulated of Sunnis and vice versa in a revenge cycle that still reverberates today.

It was always a given that Hussein's removal and free elections would lead to an ascendancy of Shiite religious parties, given their popularity and the fact that Shiites make up a majority of Iraq's population. That many Sunni Arabs would lose out in a post-Saddam Iraq, and resent this, was also a given.

But much of the current hatred revolves around very recent political choices. Most of the Shiite Islamist politicians who lead Iraq today lost multiple friends and family members in a crackdown, brutal even for the Hussein regime, on underground Shiite political movements after the first Gulf War. Today they view securing the political and military ascendancy of their sect as the top priority.

The Sunni Arabs of Anbar, who were bought off with state largesse during the Baath years, are viewed by Maliki and other leading Shiites as a potential threat to this goal. His government's systematic persecution of prominent Sunni Arab political figures is a key reason that ISIS has such a strong opening in Iraq right now.